<h2>Problem 193</h2>
<div style="color:#666;font-size:80%;">10 May 2008</div><br />
<div class="problem_content">
<p>A positive integer <var>n</var> is called squarefree, if no square of a prime divides <var>n</var>, thus 1, 2, 3, 5, 6, 7, 10, 11 are squarefree, but not 4, 8, 9, 12.</p>

<p>How many squarefree numbers are there below 2<img src="" style="display:none;" alt="^(" /><sup>50</sup><img src="" style="display:none;" alt=")" />?</p>

</div><br />
